Explore the vast range of titles available.

Inorganic solid‐state electrolytes (SSEs) are nonflammable alternatives to the commercial liquid‐phase electrolytes. This enables the use of lithium (Li) metal as an anode, providing high‐energy density and improved stability by avoiding unwanted liquid‐phase chemical reactions. Among the different types of SSEs, the garnet‐type electrolytes witness a rapid development and are considered as one of the top candidates to pair with Li metal due to their high ionic conductivity, thermal, and electrochemical stability. However, the large resistances at the interface between garnet‐type electrolytes and cathode/anode are the major bottlenecks for delivering desirable electrochemical performances of all‐solid‐state batteries (SSBs). The electrolyte/anode interface also suffers from metallic dendrite formation, leading to rapid performance degradation. This is a fundamental material challenge due to the poor contact and wettability between garnet‐type electrolytes with electrode materials. Here, we summarize and analyze the recent contributions in mitigating such materials challenges at the interface. Strategies used to address these challenges are divided into different categories with regard to their working principles. On one hand, progress has been made in the anode/garnet interface, such as the successful application of Li‐alloy anode and different artificial interlayers, significantly improving interfacial performance. On the other hand, the desired cathode/garnet interface is still hard to reach due to the complex chemical and physical structure at the cathode. The common methods used are nanostructured cathode host and sintering additives for increasing the contact area. On the basis of this information, we present our views on the remaining challenges and future research of electrode/garnet interface. This review not only motivates the need for further understanding of the fundamentals, stability, and modifications of the garnet/electrode interfaces but also provides guidelines for the future design of the interface for SSB. This review summaries recent publications related to interfacial challenges of garnet electrolyte‐based all‐solid‐state Li‐ion batteries (garnet‐ASSLIBs). The review has identified the properties of the interface, analyzed the state‐of‐the‐art methods mitigating the challenges at the interface, and proposed new opportunities in this area

Energy level mismatches between semiconductors and cocatalysts often induce carrier recombination, limiting photocatalytic and photoelectrochemical (PEC) efficiency. Here, we integrate Pt nanocluster-Fe single-atom pairs with CuO to regulate both solid-solid and solid-liquid interfaces in PEC systems. Experimental and theoretical analyses reveal that an Ohmic contact at the CuO/Pt interface accelerates electron extraction, while Pt-to-Fe charge transfer enhances oxygen reduction at Fe sites, collectively boosting reaction kinetics. Leveraging this, we construct a PEC biosensor exploiting chelating effect of glyphosate on CuO to impede electron transfer, achieving a detection limit of 0.41 ng/mL. This interface engineering strategy advances cocatalyst design for enhanced energy conversion and sensing applications by simultaneously addressing carrier dynamics and interfacial reaction barriers. Efficient electron extraction in photoelectrocatalysts requires matching energy levels between semiconductors and catalysts. Here, the authors show this matching enhances electron extraction from copper oxide by combining platinum nanoclusters and iron single-atom catalysts.

Accurate modeling of long-range forces is critical in atomistic simulations, as they play a central role in determining the properties of material and chemical systems. However, standard machine learning interatomic potentials (MLIPs) often rely on short-range approximations, limiting their applicability to systems with significant electrostatics and dispersion forces. We recently introduced the Latent Ewald Summation (LES) method, which captures long-range electrostatics without explicitly learning atomic charges or charge equilibration. We benchmark LES on diverse and challenging systems, including charged molecules, ionic liquids, electrolyte solutions, polar dipeptides, surface adsorption, electrolyte/solid interfaces, and solid-solid interfaces. Here we show that LES can reproduce the exact atomic charges for classical systems with fixed charges and can infer dipole and quadrupole moments, as well as the dipole derivative with respect to atomic positions, for quantum mechanical systems. Moreover, LES can achieve better accuracy in energy and force predictions compared to methods that explicitly learn from charges. Long-range interactions are challenging for machine learning interatomic potentials (MLIPs). Here, authors show that, by just learning from energies and forces, MLIPs can accurately capture electrostatics and predict atomic charges.

Interfaces within batteries, such as the widely studied solid electrolyte interface (SEI), profoundly influence battery performance. Among these interfaces, the solid–solid interface between electrode materials and current collectors is crucial to battery performance but has received less discussion and attention. This review highlights the latest research advancements on the solid–solid interface between lithium metal (the next-generation anode) and current collectors (typically copper), focusing on factors affecting the Li-current collector interface and improvement strategies from perspectives of current collector substrate (lithiophilicity, crystal facets, mechanical properties, and topological structure), electrolyte chemistry, current density, stacking pressure, SEI, electric field and temperature, and provides a future directions and opportunities on this topic.

The diffusion of hydrogen atoms across solid oxide surfaces is often assumed to be accelerated by the presence of water molecules. Here we present a high-resolution, high-speed scanning tunneling microscopy (STM) study of the diffusion of H atoms on an FeO thin film. STM movies directly reveal a water-mediated hydrogen diffusion mechanism on the oxide surface at temperatures between 100 and 300 kelvin. Density functional theory calculations and isotope-exchange experiments confirm the STM observations, and a proton-transfer mechanism that proceeds via an H₃O⁺-like transition state is revealed. This mechanism differs from that observed previously for rutile TiO₂(110), where water dissociation is a key step in proton diffusion.

Resolving individual atoms has always been the ultimate goal of surface microscopy. The scanning tunneling microscope images atomic-scale features on surfaces, but resolving single atoms within an adsorbed molecule remains a great challenge because the tunneling current is primarily sensitive to the local electron density of states close to the Fermi level. We demonstrate imaging of molecules with unprecedented atomic resolution by probing the short-range chemical forces with use of noncontact atomic force microscopy. The key step is functionalizing the microscope's tip apex with suitable, atomically well-defined terminations, such as CO molecules. Our experimental findings are corroborated by ab initio density functional theory calculations. Comparison with theory shows that Pauli repulsion is the source of the atomic resolution, whereas van der Waals and electrostatic forces only add a diffuse attractive background.

Surface activation: Changing facets Single crystals of titanium dioxide (TiO 2 ), with highly reactive surfaces, show promise for energy and environmental applications. Unfortunately, the highly reactive surfaces tend to disappear during crystal growth as a result of the minimization of surface energy. Most available samples of anatase, a naturally occurring crystalline form of TiO2, are therefore dominated (to over 90%) by thermodynamically stable {101} facets, rather than the more reactive {001} type. Hua Gui Yang et al . use hydrofluoric acid treatment of anatase TiO 2 to remedy this situation. Based on theoretical predictions, they synthesized uniform anatase TiO 2 single crystals containing 47% of the reactive {001} facets. This work may pave the way for the more general use of non-metallic atoms as surface controlling agents. Extensive first principles calculations carried out show that the relative stability of facets of anatase can be switched by terminating the surfaces with fluorine. It is then demonstrated that uniform anatase single crystals with a high percentage of {001} facets can be generated using hydrofluoric acid as a structure directing agent. Subsequently, surfaces can be freed of fluorine using a simple heat treatment. Owing to their scientific and technological importance, inorganic single crystals with highly reactive surfaces have long been studied 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 . Unfortunately, surfaces with high reactivity usually diminish rapidly during the crystal growth process as a result of the minimization of surface energy. A typical example is titanium dioxide (TiO 2 ), which has promising energy and environmental applications 14 , 15 , 16 , 17 . Most available anatase TiO 2 crystals are dominated by the thermodynamically stable {101} facets (more than 94 per cent, according to the Wulff construction 10 ), rather than the much more reactive {001} facets 8 , 9 , 10 , 11 , 12 , 13 , 18 , 19 , 20 . Here we demonstrate that for fluorine-terminated surfaces this relative stability is reversed: {001} is energetically preferable to {101}. We explored this effect systematically for a range of non-metallic adsorbate atoms by first-principle quantum chemical calculations. On the basis of theoretical predictions, we have synthesized uniform anatase TiO 2 single crystals with a high percentage (47 per cent) of {001} facets using hydrofluoric acid as a morphology controlling agent. Moreover, the fluorated surface of anatase single crystals can easily be cleaned using heat treatment to render a fluorine-free surface without altering the crystal structure and morphology.

From grain boundaries and heterojunctions to manipulating 2D materials, solid-solid interfaces play a key role in many technological applications. Understanding and predicting properties of these complex systems present an ongoing and increasingly important challenge. Over the last few decades computer simulation of interfaces has become vastly more powerful and sophisticated. However, theoretical interface screening remains based on largely heuristic methods and is strongly biased to systems that are amenable to modelling within constrained periodic cell approaches. Here we present an unconstrained and generally applicable non-periodic screening approach for systematic exploration of material’s interfaces based on extracting and aligning disks from periodic reference slabs. Our disk interface method directly and accurately describes how interface structure and energetic stability depends on arbitrary relative displacements and twist angles of two interacting surfaces. The resultant detailed and comprehensive energetic stability maps provide a global perspective for understanding and designing interfaces. We confirm the power and utility of our method with respect to the catalytically important TiO 2 anatase (101)/(001) and TiO 2 anatase (101)/rutile (110) interfaces. Predicting structures and stabilities of solid-solid interfaces presents an ongoing and increasingly important challenge for development of new technologies. Here authors report an unconstrained and generally applicable non-periodic screening method for systematic exploration of material´s interfaces.

Graphene: new process yields ultraflat form Graphene is the subject of intense research thanks to its novel fundamental properties and its potential for possible electronics applications. Though graphene is essentially two-dimensional, a layer of carbon atoms just one atom thick, it is in fact always slightly crumpled. Whether laying on a substrate or suspended, it always presents ripples, which are thought to define a remarkably diverse set of the observed properties of graphene. Now a team from Columbia University has developed a simple, but effective method of producing ultraflat graphene by deposition on an atomically flat mica surface that tightly binds to the carbon atoms. Thus ripple formation is not an essential feature of high-quality graphene. The availability of ultraflat samples will facilitate studies of the effect of ripples on the physical and electronic properties of graphene. Graphene, an atom-thin carbon sheet is interesting for its fundamental properties as well as for its possible applications in electronics, is not strictly two-dimensional. Microscopic corrugations, or ripples, have been observed in all graphene sheets so far. Direct experimental study of the physics of such ripples has been hindered by the lack of flat graphene layers. Ultraflat graphene is now achieved through its deposition on the atomically flat terraces of cleaved mica surfaces. Graphene, a single atomic layer of carbon connected by sp 2 hybridized bonds, has attracted intense scientific interest since its recent discovery 1 . Much of the research on graphene has been directed towards exploration of its novel electronic properties, but the structural aspects of this model two-dimensional system are also of great interest and importance. In particular, microscopic corrugations have been observed on all suspended 2 and supported 3 , 4 , 5 , 6 , 7 , 8 graphene sheets studied so far. This rippling has been invoked to explain the thermodynamic stability of free-standing graphene sheets 9 . Many distinctive electronic 10 , 11 , 12 and chemical 13 , 14 , 15 properties of graphene have been attributed to the presence of ripples, which are also predicted to give rise to new physical phenomena 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 that would be absent in a planar two-dimensional material. Direct experimental study of such novel ripple physics has, however, been hindered by the lack of flat graphene layers. Here we demonstrate the fabrication of graphene monolayers that are flat down to the atomic level. These samples are produced by deposition on the atomically flat terraces of cleaved mica surfaces. The apparent height variation in the graphene layers observed by high-resolution atomic force microscopy (AFM) is less than 25 picometres, indicating the suppression of any existing intrinsic ripples in graphene. The availability of such ultraflat samples will permit rigorous testing of the impact of ripples on various physical and chemical properties of graphene.

Friction at the nanoscale For large objects sliding over one another, the friction force is proportional to the true contact area between the two bodies — which is smaller than the apparent contact area because the surfaces are rough, consisting of a large number of smaller features (asperities) that actually make the contact. The situation for nanomaterials, however, has been unclear, since the continuum contact theory that can account for macroscale effects has been predicted to break down at the nanoscale. Using large-scale molecular dynamics simulations of scanning force microscopy experiments, Yifei Mo et al . show that, despite this, simple friction laws do apply at the nanoscale: the friction force depends linearly on the number of atoms, rather than the number of asperities, that are chemically interacting across the sliding interfaces. For large objects sliding over one another, the friction force is proportional to the true contact area between the two bodies — this is smaller than the apparent contact area as the surfaces are rough, consisting of a large number of smaller features (asperities) that actually make contact. Here a related idea holds for contacts at the nanoscale: the friction force depends linearly on the number of atoms (rather than asperities) chemically interacting across the sliding interfaces. Macroscopic laws of friction do not generally apply to nanoscale contacts. Although continuum mechanics models have been predicted to break down at the nanoscale 1 , they continue to be applied for lack of a better theory. An understanding of how friction force depends on applied load and contact area at these scales is essential for the design of miniaturized devices with optimal mechanical performance 2 , 3 . Here we use large-scale molecular dynamics simulations with realistic force fields to establish friction laws in dry nanoscale contacts. We show that friction force depends linearly on the number of atoms that chemically interact across the contact. By defining the contact area as being proportional to this number of interacting atoms, we show that the macroscopically observed linear relationship between friction force and contact area can be extended to the nanoscale. Our model predicts that as the adhesion between the contacting surfaces is reduced, a transition takes place from nonlinear to linear dependence of friction force on load. This transition is consistent with the results of several nanoscale friction experiments 4 , 5 , 6 , 7 . We demonstrate that the breakdown of continuum mechanics can be understood as a result of the rough (multi-asperity) nature of the contact, and show that roughness theories 8 , 9 , 10 of friction can be applied at the nanoscale.